Watchmaker&#39;s poising tool



Jan. 2, 1940. w FRASER 2,185,843

WATCHMAKER'S POISING TOOL Filed Dec. 23, 1937 12 ,f 6. H 5 I warran.firzd'er" Patented Jan.2, 19 40 i I I Lj gg ggagg I UNITED STATESPA'I'EII'I'v QFF'i-i'.

. WATCHMAKERS .POISING 'roon Warren 15. Fraser, Westboro, Mass.Application De ember 23, 1937, Serial No. 181,390 8- Claims. (01. 73-51)" The present invention relates to tools, used by will be apparentfrom the following detailed de -i watchmakers to test the balanceassembly of a scriptidn t ke i connection with the following watch inorder to insure that its center of gravity v drawing ,in which--coincides with its pivotalaxis. Fig. 1 is a side elevation, partially insection, of

5 The present device most commonly used for the tool of the invention.testing the poise of a balance assembly isfin the. Fig. 2 isan endelevation of Fig. 1. Y nature of a pair of calipers held in the handdur- Fig. 3 is an enlarged view of a balance assembly I ing the testingoperation. This type of device is ed in position to b poisedalmostuniversal in use and is depended upon to g. 4 s a Vi w taken on e j y Insecure the accuracy necessary to maintain a Fig; 5 is a'modification ofthe invention. lowatch inclose running condition regardless of Fig.Sis-an endview of Fig 5. v

the Position of the pendent but it has been no- Fig. 7 is a modificationof the invention. ticed that the oiseobtained-has not been so aci ereference c a t refer to e pars curate as has been desired for very finetimein the difierent fi j 4 -keepers. There is another type of devicewhich he po n O I s t d for -b 1 used by some clock and watch makerswhich W ch and clock makers and adju rs a i consists of apair ofparallelknifeedges that constructed n suc a m nerhatany ne hav rest on abench or other support in a perfectly. ingknowledge of the requirements.necessary to level plane. Theuse of this type of a device enassureaccurate, poise in balance assemblies can ables the operator to poise abalance assembly f readily set. the said tool ;to suit the'assembly at imore accurately than when using the caliper type hand and bring itji'ntopoise very readily. v but due to factthat the process is extremelyslowWith reference to 'Fig. 1 the invention comit is only used occasionally.I I- prises a'base or foot I having 'a r'esilient pedestal v It isaccordingly an object of the present in- 2 which supports a body 3. Thebodyt has an vention to provide a device which can be placed Opening 4 tpr vi ecl r n f0rthe Wheel fl 1."

" on a solid support whereby it will be held stable balance assembly. Oneitherside of the opening andnot affected by conditions such as existwhen flare hubs'i'and'fi having bores l and 8 in which using a hand tooland yet is simple to set up and are slidably j'mounted runners 8 and H).A

use. n j Runner .9 has a reduced end portion II and an- In-the calipertype of poising tools it is necesenlarged headportion [2, said head,portion fit- 30 sary to adjust the tool for each balanceassemblyf ting.in a bore-l3 in the hub 5. A keyway M re-Q regardless of whether theassembly is of the'same ceives a pin l5jwhereby the runner Sis axiallyor of a different size. This adjustment. requires but not rotatablymovable. The bore [3 isclosed.

a great deal of skill in order to duplicate the by a cap l6 which isscrew threaded therein. I

"and; is dependentpn a. .persons judgment as to adjusting screw I! theend of which abuts the whether the conditions are the same in.each'case. head l2 of the plungerll. Aspringw surrounds It is anotherobject of the present invention to the runner 9, one end abutting the.bottom of the. provide an adjustable poising tool which can be bore I3and the other end abutting the underside 40 used for testing the poiseof any number of balof the head l2, and urges it to the left to hold it4p 'ance assemblies of the samesize without the ne-. against the end ofthe screw l1.

cessity of individual adjustments and yet can be The runner I!) has areduced portion 48 and adjusted for various sizes of assemblies as re--flattened jsurface. l9 against which the end of a. quired. screw 20,Fig. 2, is forced to hold the saidrunner 45, In using the parallel knifeedges it is necessary. inadjusted position. A pair of caps 2| andQZZ tobe sure that they are'in positive parallel relahaving openings 23, Figs.1, 3 and 1,. are madeto tion with each other and in a level plane. Thisbe a friction fit on the reducedends ll and 48 of gives a static balanceto the balance assembly but the-runners 9 and I 0 whereby they can beadjustit is a very difficult and tedious operation to per ed lengthwise.The caps 2i and 22 "also have 50 form. arcuate knife edges 24 and 25 onwhich are placed 5 It is a iurther'object of the present invention tothe ends 26 and 21 of the balance assembly staff. 1 test a balanceassembly for poise by means'of a Due to. the fact that the weight of abalance; solidly supported poising tool in which vibratory assembly isvery small in amount the surface impulses can beset up. friction betweenthe ends 26 and 2'! and the knife Other and ancillary objects andadvantages edges and 25 is enough to prevent accurate;

exact conditions for each balanceassembly tested The cap I6 isinternally-threaded to receive an.

' of poise.

poising of the said assembly by pure static balancing and, therefore,vibration is used to cause the assembly to move so that its heavy sidemoves to. the bottom. The preferred construction of the tool as shown inthe drawing, Figs. 1 and 5, is in the nature of a tuning fork in whichone prong is used for a supporting base and the other prong used fortransmitting vibratory impulses, the two prongs being connected by aresilient portion at one end, although it is possible to mount a body ona pair of coil springs as shown in Fig. 7. It is also possible toconstruct the body member to have a fiat upper surface with the runnersraised.

high enough to provide clearance for the balance wheel without thenecessity of having a clearance I provided. In order to provide theproper amount of vibration to the poising tool a knurled member 28, Fig.1, is fitted in a bore 29 provided in the body 3. By stroking theknurled member 28 with any instrument having a sharp corner or anotherknurled member, such as a round file,

vibrations in a vertical plane are set up due to the' resiliency of thepedestal 2. These vibrations are suificient to cause the balanceassembly to raise off of the knife edges 24 and 25 just enough topermitthe said assembly to rotate if it is out When an assembly is in poise itwill stay in any position it is placed regardless of the vibrationsimparted to the tool.

By having the openings 23 in the caps Zland 22 it is possible to placethe balance assembly staff ends 26 and 21 on the knife edges withoutdisturbing the axial setting of the runners 9 and Ill.

Figs. 5 and 6 show a modified construction of the invention wherein thebase 38 is separate from the body 30' and is fastened thereto by meansof screws 3|.

The modification shown in Fig. '7 provides for mounting a body 32 on theupper end of a pair of springs .33, 34 which are secured tosaid body inany suitable manner such as soldering. The lower ends of the saidsprings are securely fastened to a base 35. A knurled'member 36 isfastened to the bottom of the body 32 so that when the said member isstroked with a tool vibratory impulses will be set up in a verticalplane. While the members 28 and 36 arepreferably knurled they could bereplaced with members having a serrated edge provided the serrationswere fine enough to set up the proper vibrationary impulses.

When using the poising tool of this invention the arbor I0 is fastenedin desired-position by means of the clamping screw 20 and then the arbor9 is adjusted by means of the screw 1! so that the ends 26 and 21' ofthe balance staff just clear the faces of the said arbors when the bal-'ance assembly is lowered through the openings 23, in the caps 21 and 22,onto the knife edges 24 and 25. With the balance assembly in positionthe knurled member 28 is stroked with a tool, such. as a file, to set upvibrations in the tool so that the said assembly will gravitate so thatits heavy side will be on the bottom. The assembly is removed from theknife edges and a correction made therein to bring the assembly intobalance.

This operation is repeated until the assembly can be placed in the toolwith anypart of the rim of the balance wheel at the bottom of the caps2| and 22 and stay there without gravitation when the tool is vibrated.When this condition is reached the assembly is poised to a very highdegree of accuracy and is capable of running in a watch very closely inall positions of the pendent.

vI claim:

1. In a balance assembly poising tool having a base member, a bodymember having arcuate means to support the ends of. a balance assembly,resilient means forming the sole connection between said members, andmeans attached to said body member whereby relative vibration in avertical plane may be set up between said members.

2. In a balance assembly poising tool having a base member, a bodymember having arcuate means to support the ends of a balance assembly,resilient means forming the sole connection between said members at apoint substantially to one side of the balance assembly supportingmeans, and means attached to said body member whereby relative vibrationin a vertical plane may be set up' between said members.

3. In a poising tool having a base membena body member with arcuateknife edge supports for a' balance assembly, resilient means forming thesole connection between said members at one end thereof, and meansattached'to said body member comprising a knurled member whereby"relative vibration in a vertical plane can be set connection betweensaid members at one end thereof, opposed runners having arcuate supportsto receive the ends of a balance staff in said body member, and means torelatively ad 7. In a poising tool comprising a base member,

a body member having an opening therein to receive a balance assembly,resilient meansconnecting said members, and opposed arcuate knife edgessupported on said body member at each side of the openingand adapted tosupport the ends oi. the balance staff.

8. In a poising tool comprising a base member, a body member, resilientmeans forming the sole connection between said members atone endthereoifiand opposed runners in said body member provided with arcuateknife edges.

WARREN F. FRASER. Y

